Drilling Apparatus

Abstract

The apparatus includes two telescoping members connected into a drill string just above the bit. Relative axial movement of the members rotates the lower, driven, member relative to the driving member in the direction of rotation of the bit. This results in an increase in the speed of rotation of the bit due to axial vibration of the bit as it is rotated on the bottom of a well bore.

Description

This invention relates to drilling apparatus.

To cause a drill bit to penetrate the earth, it is held against the bottom of the well bore with considerable force. This is usually referred to as the weight on the bit, or drilling weight, and commonly runs into the tens of thousands of pounds of force. As the bit is rotated, while subjected to this force and in engagement with the bottom of a well bore, it will tend to bounce off of the bottom causing axial vibrations to be set up in the drill string. This is particularly true of bits employing cone-shaped cutters that roll around the bottom of the hole and that have protruding teeth that move into and out of engagement with the bottom of the hole as the cone rotates. The vertical vibration produced during drilling operations is considered to be undesirable since it is damaging to bit bearings and other downhole equipment. Therefore, efforts have been made to absorb it to reduce its damaging effect, particularly when a downhole motor is located above the bit, by placing an impact absorbing sub above the bit in the drill string. One such tool presently being used is known as the Gist shock tool.

It is an object of this invention to use the vertical vibrations normally produced in the drill string by a rotating drill bit to increase the rotational speed of the drill bit above that of the drill string. Usually, additional rotational speed of the bit is desirable. This is particularly true as the well bores get very deep, and in addition it is desirable to convert the vibrational energy produced by the drill bit to rotational energy thereby tending to dampen such vibrations.

It is a further object of this invention to provide drilling apparatus that will transmit the desired drilling weight from the drill string to the drill bit and that will also rotate the drill bit at the speed of rotation of the drill string and that further will increase the speed of rotation of the bit relative to the drill string by an amount proportional to the frequency of vibrations imposed in the drill string by the drill bit rotating against the bottom of a well bore.

It is a further object of this invention to provide a driving member for rotating a driven member which, in turn, rotates a drill bit with the driving member connected to the drilling member in such a manner that axial relative movement of the two members will produce an increase in rotational speed of the driven member over the driving member to thereby increase the rotational speed of the bit.

These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached drawings and appended claims.

In the drawings:

FIG. 1 is a view in elevation of the lower end of a conventional drill string, including the apparatus of this invention;

FIGS. 2A and 2B are vertical sectional views through the preferred embodiment of the apparatus of this invention;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2A; and

FIGS. 4A - 5C are simplified drawings of the structure of the preferred embodiment that increases the rotation of the drill bit over that of the drill string as a result of axial vibrations of the drill bit.

FIG. 1 shows how the apparatus of this invention is connected into a drill string. Preferably, the apparatus will be connected between the bottom of the drill pipe and the bit, although it could be located in other places in the drill string. As shown in FIG. 1, however, housing 10, which comprises the driving member of the apparatus, is connected to the lower end of drill pipe 11. This portion of the drill pipe string will probably be made up of a plurality of drill collars that are used to force the drill bit against the bottom of the hole with the desired drilling weight. Mandrel 14 which, in the embodiment shown, comprises the driven member of the apparatus is connected to and rotates the drill bit. As shown, the mandrel is connected directly to drill bit 12. In some cases, however, the connection may be made through one or more other members, such as stabilizers and bit subs.

Referring now to FIGS. 2A and 2B, means are provided for connecting the driving member of the apparatus to the driven member for limited relative axial movement of the members. In the embodiment shown, mandrel 14 extends into tubular housing 10 as shown in the drawings. The internal diameter of the housing varies to provide internal cavities of varying size. Cavity 15 is bounded on one side by upwardly facing shoulder 16 and on the other by downwardly facing shoulder 17. Bearing 18 encircles portion 19 of the mandrel and is clamped thereto between upwardly facing shoulder 20 on the mandrel and bearing cap 21 that is connected to the mandrel by threads 22. With this arrangement, bearing 18 allows relative rotation between mandrel 14 and housing 10 and limits the downward movement of the mandrel relative to the housing, the limit being determined by the arrangement of the bearing with upwardly facing shoulder 16.

Resilient means are provided for resisting axial movement in one direction to transmit drilling weight imposed by the drill string on the driving member to the driven member and a drill bit attached thereto while allowing limited relative axial movement of the members due to axial vibrations of the driven member due to the rotation of the drill bit in engagement with the bottom of the well bore. In the embodiment shown, coil spring 24 encircles portion 25 of the mandrel. Its upper end engages downwardly facing shoulder 26 of the housing. Its lower end engages cup-shaped member 27 which transfers the load of the downward force produced by the coil spring to the outer race of bearing 18. In operation, when drill bit 12 engages the bottom of the well bore, drill string 11 is used to provide drilling weight to the bit in the conventional manner. As this weight is imposed on housing 10, it will telescope downwardly over mandrel 14, compressing spring 24, which, in turn, will transfer the drilling weight to mandrel 14 and to drill bit 12.

In rotary drilling, drilling fluid is normally pumped down the drill pipe making up the drill string and out openings in the drill bit to cool the bit and to carry the cuttings away. In the embodiment shown, drilling fluid flows from drill string 11 into mandrel 14 through the connection shown in FIG. 2B. The lower end of the drill pipe is connected to housing 10 through a conventional tool joint, as shown. Pin 30 of the tool joint clamps tubular member 31 and packing gland assembly 32 between the lower end of the pin and upwardly facing shoulder 33 in the housing. Tubular member 31 acts as an extension of passageway 11a through which drilling fluid flows as it is pumped down through the drill pipe. The upper end of mandrel 14 is designed to telescope over tubular member 31 as the mandrel telescopes within housing 10 due to the compression of spring 24 by the weight imposed on the housing by the drill string. Seal ring 34 of gland assembly 32 is compressed between rings 32a and 32b and provides a sliding seal between the upper end of the mandrel and the housing sufficient to insure that most of the drilling fluid flows into the mandrel with little or no fluid loss.

The inside of housing 10 is maintained full of lubircating oil so that the operating parts therein that will be described below will be isolated from the drilling fluid which, in most ases, will contain some abrasives. In order to maintain the pressure inside the housing equal to the pressure outside thereof, the inside of the housing is connected to chamber 36 by ports 37 (FIG. 2B). Flexible diaphragm 38 is exposed on one side to the outside pressure and on the inside to the fluid on the inside of the housing, and therefore the fluid inside the housing will be maintained at the same pressure as the fluid outside. At the lower end of housing 10, seal ring 39 encircles mandrel 14 and provides a seal between the lower end of the housing and the mandrel to keep the lubricating oil inside of the housing above the seal isolated from the drilling fluid outside thereof.

Means are provided for transmitting the rotation of the driving member by the drill string to the driven member and the drill bit and to convert the vertical vibrations of the driven member to rotational movement relative to the driving member to cause the driven member and the drill bit attached thereto to rotate faster than the driving member. In the embodiment shown, two drive collars 44 and 45 are located in housing 10 between upwardly facing shoulder 46 and downwardly facing shoulder 47.

Means are provided to mount the collars in the housing for rotation relative to the housing in the desired direction of rotation of the bit, but not in the opposite direction. In the embodiment shown, ball bearings 48 are located between the collars and the oppositely facing shoulders and between the collars themselves. This allows relative rotation of the collars and the housing and relative rotation between the collars themselves while maintaining the collars fixed relative to their position in housing 10. As best seen in FIG. 3, collar 44 carries a plurality of members 50 in an annular groove on the outside of the collar. These members are eliptical in cross section and are positioned so that relative rotation between the collar and the housing in one direction is allowed, whereas such relative rotation in the other direction is prevented. This is the principle used in what is commonly known as a Sprag clutch. Thus, as shown in FIG. 3, collar 44 can rotate relative to housing 10 in the direction of the arrow, which is the direction that the bit is conventionally rotated, but it cannot rotate in the opposite direction relative to the housing. Collar 45 is provided with a similar clutch. This allows the collars to rotate faster than the housing, but not slower, and rotation of the housing by the drill string will be transmitted to both collars to rotate mandrel 14 and the bit.

The torque is transmitted from collars 44 and 45 to mandrel 14 through engaging surfaces on the two members. In the embodiment shown, the surface of the mandrel adjacent the collars is provided with a plurality of equally spaced grooves that form a plurality of equally spaced splines or lugs. The inside surfaces of the collars also have a plurality of equally spaced grooves and splines that mate with the grooves and splines or lugs on the mandrel to form a driving connection between the collars and the mandrel. For simplicity, in FIG. 2A the grooved surface on the mandrel is indicated by a plurality of lines with each line representing a tooth or spline. One set of splines 52 are inclined to the longitudinal axis of the mandrel in one direction, while the other set of splines 56 are inclined at the same angle but in the opposite direction. The teeth on one drive collar extend into one set of inclined grooves on the mandrel while the teeth on the other collar extend into the other set of grooves. The collar teeth are numbered 54 for drive collar 44 and 55 for drive collar 45. In this embodiment, teeth or splines 52 mesh with teeth 54 on collar 44 and splines 56 mesh with teeth 55 on drive collar 45. As explained above, splines 52 and 56 are inclined from the longitudinal axis of the mandrel in opposite directions. It is this arrangement, along with the arrangement with the drive collars that converts vertical vibration imposed on the mandrel by the drill bit to rotation of the bit relative to the housing and the drill pipe to increase the speed of rotation of the bit.

How this is accomplished will be explained, with reference to FIGS. 4A - 5C. In these figures, only one tooth 52 and two teeth 54 on collar 44 that engage spline 52 are shown in FIGS. 4A - 4C. In FIGS. 5A - 5C, oppositely inclined spline or tooth 56 and engaging teeth 55 of collar 45 are shown. In all of these figures, the bit is being rotated clockwise as viewed from the top of the bit so that the members will be moving to the left as shown by the arrow.

Assume that the teeth are in the position shown in FIG. 4A, and the first vibration causes the mandrel to move upwardly relative to the housing. This will cause tooth 52 to move upwardly relative to teeth 54 on collar 44. Being inclined, as shown, tooth 52 will have to move further to the left, as shown in FIG. 4B, by the distance dR if it moves through a stroke S due to the vibration of the bit. This upward movement, then, has caused the mandrel and the bit to move ahead of the housing by the distance dR.

As the mandrel moves up causing this relative rotation, oppositely inclined tooth 56 moves between teeth 55 from the position of FIG. 5A to the position shown in FIG. 5B through the same distance of stroke S. This movement will cause teeth 55 and collar 45 to rotate around the axis of the housing in the direction of the drill bit by the distance 2dR, as shown in FIG. 5B. One dR results from the advance of the mandrel by teeth 52 and 54. The other dR results from the relative movement of teeth 55 and 56. This rotation will have no effect on the speed of the drill bit since the clutch between collar 45 and the housing will allow this relative rotation. The collar then simply free wheels as tooth 56 moves upwardly to the position shown in FIG. 5B. Upward movement, then, due to vibration, will cause a change in the position of the bit relative to housing 10 by a distance dR.

By definition, of course, vibration means an oscillating movement, so we can assume that the mandrel will move down after it has moved up. The distance it moves up or down will vary, but for our purposes it is assumed that the up and down stroke are approximately equal. On the downward movement of mandrel 14 relative to the housing, tooth 56 moving through a stroke S from its position in FIG. 5B, will cause the mandrel and the bit to move ahead of the housing again by the distance dR, since either teeth 55 or tooth 56 must rotate to accommodate this change in position and teeth 55 cannot rotate in the direction necessary to do this. At the same time, tooth 52 moving downwardly between teeth 54 to the position shown in FIG. 4C, will cause collar 44 to free wheel and move ahead of the housing by the distance 2dR but will cause no change in the rotational speed of either the bit or the housing. During the time that spline or tooth 52 is moving upwardly and advancing the bit, the driving connection between the housing and the bit is through teeth 54 of collar 44 and teeth 52 of the mandrel. Conversely, when tooth 56 is advancing the bit by a distance dR on the down stroke, the driving connection between the housing and the bit is through teeth 55 of collar 45 and teeth 56 of the mandrel.

Thus, with this arrangement, as the bit vibrates on the bottom causing mandrel 14 to reciprocate vertically relative to the housing, the speed of rotation of the bit will be increased by an amount determined by the frequency of vibration and the distance that the bit is advanced during each vibration by the action of the inclined teeth on the mandrel and the drive collars.

It may be desirable to mount the collars on the driven member, mandrel 14, and the oppositely inclined splines on the inside wall of housing 10. The only change required with this arrangement is for the clutch between the collars and the mandrel to allow relative rotation between the collars and the mandrel in the direction opposite the direction of rotation of the bit.

The operation of such a reversal of parts can be explained with reference to FIGS. 4A - 5C. Assume that teeth 54 and 55 are carried by collars mounted on mandrel 14 and teeth 52 and 56 are on the inside surface of housing 10. Also, assume that teeth 52 and 56 are being observed in elevation on the housing so that now the teeth are moving to the right as shown by the arrows shown dotted. Downward movement of the mandrel due to bit vibration will move teeth 52 and 54 of FIG. 4A to the position shown in FIG. 4B and advance the bit relative to the housing the distance dR. Collar 55 carrying teeth 55 will be rotated in the direction opposite the direction of bit rotation and will free wheel. It will not move the distance 2dR as shown in FIG. 5B, however, but only one dR, since it is moving in the opposite direction from the direction of rotation of the housing. On the upward movement of the mandrel, tooth 56 becomes the driver through collar 45 and collar 44 free wheels.

From the foregoing, it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the apparatus of this invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Claims

The invention having been described, what is claimed is:

1. Apparatus for locating in a drill string to transmit rotation and drilling weight from the drill string to a drill bit in engagement with the bottom of a well bore, comprising a driving member for connecting to a drill string, a driven member for connecting to a drill bit, means connecting the driving member and the driven member for limited relative axial movement, resilient means for resisting such axial movement in one direction to transmit drilling weight imposed by the drill string on the driving member to the driven member and a drill bit attached thereto while allowing relative axial movement of the members produced by any axial vibrations of the driven member due to rotation of a drill bit in engagement with the bottom of a well bore, and means for transmitting the rotation of the driving member by the drill string to the driven member and a drill bit attached thereto and to convert the vertical vibrations of the driven member to rotational movement relative to the driving member to cause the member and a drill bit attached thereto to rotate faster than the driving member.

2. The apparatus of claim 1 in which the driving member comprises a tubular housing and the driven member comprises a mandrel having a portion thereof extending into the housing.

3. The apparatus of claim 1 in which the rotation transmitting means comprises first and second drive collars mounted on the driving member for rotation relative to said member in the direction of desired rotation of the driven member, surfaces on each collar in engagement with surfaces on the driven member to transmit rotation of the driving member to the driven member, one of said engaging surfaces on one of the collars or the driven member being inclined to the longitudinal axis of the members so that relative movement of the members in one axial direction due to bit vibration will cause the driven member to rotate relative to the driving member in the direction of rotation of the bit and one of said engaging surfaces on the other collar and member being inclined in the opposite direction to the other inclined surface to cause relative rotation of the driven member to the driving member in the desired direction of rotation of the bit when the driven member moves axially in the opposite direction due to vibration of a drill bit.

4. The apparatus of claim 1 in which the rotation transmitting means comprises first and second drive collars mounted on the driven member for rotation relative to said member in the opposite direction from the desired rotation of the driven member, surfaces on each collar in engagement with surfaces on the driving member to transmit rotation of the driving member to the driven member, one of said engaging surfaces on one of the collars or the driven member being inclined to the longitudinal axis of the members so that relative movement of the members in one axial direction due to bit vibration will cause the driven member to rotate relative to the driving member in the direction of rotation of the bit and one of said engaging surfaces on the other collar and member being inclined in the opposite direction to the other inclined surface to cause relative rotation of the driven member to the driving member in the desired direction of rotation of the bit when the driven member moves axially in the opposite direction due to vibration of a drill bit.

5. Apparatus for driving a drill bit comprising a housing, a mandrel having a portion extending into the housing and a portion extending out of the housing for connecting to a drill bit to rotate the bit with the mandrel and to transmit a downward force imposed on the mandrel to the bit, resilient means located in the housing to transmit any downward force on the housing to the mandrel while allowing the mandrel to reciprocate axially relative to the housing due to vibrations produced by a bit as it is urged against the bottom of a well bore by a downward force, and means carried by the housing and the mandrel to transmit the rotation of the housing to the mandrel and to cause relative rotation of the mandrel and the housing in the direction the mandrel is rotated by the housing as the mandrel reciprocates axially in the housing due to vibration of the bit to increase the speed of rotation of the bit relative to the housing.

6. The apparatus of claim 5 in which the means for transmitting the rotation of the housing to the mandrel and for causing such relative rotation to increase the speed of rotation comprises first and second drive collars mounted in the housing and encircling the mandrel, means mounting the collars for rotation relative to the housing in the desired direction of rotation of the mandrel and a bit connected thereto and to hold the collars from rotating relative to the housing in the opposite direction, each collar having a tooth or a groove to engage a tooth or a groove on the mandrel with the groove associated with one collar being inclined from the longitudinal axis of the mandrel in one direction to cause relative rotation of the mandrel and the collar in the direction of rotation of the bit when the mandrel moves axially relative to the housing in one direction and with the groove associated with the other collar being inclined in the opposite direction to cause relative rotation of the mandrel and the housing in the direction of rotation of the bit when the mandrel moves axially in the other direction.

7. The apparatus of claim 5 in which the means for transmitting the rotation of the housing to the mandrel and for causing such relative rotation to increase the speed of rotation comprises first and second drive collars mounted on the mandrel and encircling the mandrel, means mounting the collars for rotation relative to the mandrel in the opposite direction of rotation of the mandrel and a bit connected thereto and to hold the collars from rotating relative to the housing in the opposite direction, each collar having a tooth or a groove to engage a tooth or a groove on the mandrel with the groove associated with one collar being inclined from the longitudinal axis of the mandrel in one direction to cause relative rotation of the mandrel and the collar in the direction of rotation of the bit when the mandrel moves axially relative to the housing in one direction and with the groove associated with the other collar being inclined in the opposite direction to cause relative rotation of the mandrel and the housing in the direction of rotation of the bit when the mandrel moves axially in the other direction.